[cantstopthefeeling]

Hi guys!

I recently purchased a 2015 535i xDrive. I have a few DIY projects on my hands, but otherwise, the car is in immaculate condition. My biggest gripe is this high pitch sound when the MPG gauge goes up and the blue EfficientDynamics label is illuminated. It's so high that it's noticeable over AC and radio at low to moderate volumes. It's not ear piercing but just loud enough to hear and be annoying. I tried having my dad listen, but his ears must not work well enough anymore! Anyone have any advice?

[thakid22]

Originally Posted by cantstopthefeeling

Hi guys!

I recently purchased a 2015 535i xDrive. I have a few DIY projects on my hands, but otherwise, the car is in immaculate condition. My biggest gripe is this high pitch sound when the MPG gauge goes up and the blue EfficientDynamics label is illuminated. It's so high that it's noticeable over AC and radio at low to moderate volumes. It's not ear piercing but just loud enough to hear and be annoying. I tried having my dad listen, but his ears must not work well enough anymore! Anyone have any advice?

Efficient Dynamics (Blue) simply means the alternator is charging at that time.
It sounds like your alternator is making a whine when it charges.

Your solution will likely involve replacing your alternator with a new one.

[cantstopthefeeling]

Originally Posted by thakid22

Efficient Dynamics (Blue) simply means the alternator is charging at that time.
It sounds like your alternator is making a whine when it charges.

Your solution will likely involve replacing your alternator with a new one.

Hi Thakid22,

Thanks for the quick reply. Any idea the rough cost on this? I was under the impression the alternator should charge at all times during driving rather than just when my foot is off the pedal and that light is illuminated. I'm not too familiar with the 535 set up though and could certainly be wrong. Also, I've noticed, I hear the sound a lot less when I go into Eco Pro mode.

[HighlandPete]

Originally Posted by cantstopthefeeling

Hi Thakid22,

Thanks for the quick reply. Any idea the rough cost on this? I was under the impression the alternator should charge at all times during driving rather than just when my foot is off the pedal and that light is illuminated. I'm not too familiar with the 535 set up though and could certainly be wrong. Also, I've noticed, I hear the sound a lot less when I go into Eco Pro mode.

Energy management is controlling alternator charging rate to save fuel. It is not like a conventional charging system, according to the battery SOC (state of charge) it can be very limited. Maximum charging rate takes place when you completely lift off the gas and/or are braking.

It could be a sign of a failing alternator, but check out the serpentine drive belt/assembly as well, before any assumption it is definitely a faulty alternator.

PS: Does the same sound occur if you are stationary and switch on high energy consumers like heated seats, rear heated window, etc.?

[cantstopthefeeling]

Originally Posted by HighlandPete

Energy management is controlling alternator charging rate to save fuel. It is not like a conventional charging system, according to the battery SOC (state of charge) it can be very limited. Maximum charging rate takes place when you completely lift off the gas and/or are braking.

It could be a sign of a failing alternator, but check out the serpentine drive belt/assembly as well, before any assumption it is definitely a faulty alternator.

PS: Does the same sound occur if you are stationary and switch on high energy consumers like heated seats, rear heated window, etc.?

Ok, so I have an update. I turned on both vented and heated front seats, rear defrost, AC all while the vehicle was at idle and the noise never came on. It is only on when I lift my foot from the accelerator. This is funny, but I found the sound on a video. It's at 8:15 and turns off at 8:33 in the video. Hopefully your speakers pick it up! PLEASE HELP!

[Surly73]

Personally, I'd do further investigation before replacing the alternator.

The alternator charges all the time. The ED thing indicates that your alternator *might* be charging at a lower target voltage until ED kicks in, at which time the target voltage goes to 14.8VDC (maximum permissible for AGM batteries)

*IF* your battery state of charge is below 80%, the ED gauge is meaningless and the system targets 14.8VDC all the time. ED is mostly marketing. I've confirmed this all with a voltmeter in my F10. [ I get that every little bit helps fuel ecomony, and it's all done in software so why not - my issue is with all the people who have been sold thinking it is a sophisticated system of "regenerative braking" etc... ]

Before spending a thousand bucks swapping out your alternator at a shop I would also entertain the possibility that the correlation with the ED indicator is coincidence, and you may be hearing bearing whine from a driveline component like the transfer case, transmission, differential etc... When the ED bar lights up, the fuel injectors are also completely off, which alters engine braking and a few other characteristics.

Personally, I would use the manual shifting ability of the car to determine if the noise changes character with engine RPM at all. Everything "after" the transmission will change pitch/character with road speed (so being in 5th or 8th won't affect the noise). Everything "before" the transmission (including everything driven by the serpentine belt) will change pitch/character with engine speed (meaning that what gear you're in matters).

Some shops will also have a microphone set up where they can stick microphones all over the car near suspect components and then listen from a laptop in the car while its being driven. That could also confirm whether you're looking at alternator or not.

Work with passengers too to determine if the noise is from the front or rear etc...

Just my two cents - before spending a wad of money and possibly not fixing the problem. There was a guy in F10 forums earlier talking about a groaning or rumbling when the ED bar was lit. I believe it was his transfer case (completely unrelated to ED, but related to engine braking).

[HighlandPete]

Originally Posted by cantstopthefeeling

Ok, so I have an update. I turned on both vented and heated front seats, rear defrost, AC all while the vehicle was at idle and the noise never came on. It is only on when I lift my foot from the accelerator. This is funny, but I found the sound on a video. It's at 8:15 and turns off at 8:33 in the video. Hopefully your speakers pick it up! PLEASE HELP!

Can't hear anything on the video ???

Was there any change with increasing engine revs? (More load on the alternator).

[thakid22]

Originally Posted by Surly73

Personally, I'd do further investigation before replacing the alternator.

The alternator charges all the time. The ED thing indicates that your alternator *might* be charging at a lower target voltage until ED kicks in, at which time the target voltage goes to 14.8VDC (maximum permissible for AGM batteries)

*IF* your battery state of charge is below 80%, the ED gauge is meaningless and the system targets 14.8VDC all the time. ED is mostly marketing. I've confirmed this all with a voltmeter in my F10. [ I get that every little bit helps fuel ecomony, and it's all done in software so why not - my issue is with all the people who have been sold thinking it is a sophisticated system of "regenerative braking" etc... ]

Before spending a thousand bucks swapping out your alternator at a shop I would also entertain the possibility that the correlation with the ED indicator is coincidence, and you may be hearing bearing whine from a driveline component like the transfer case, transmission, differential etc... When the ED bar lights up, the fuel injectors are also completely off, which alters engine braking and a few other characteristics.

Personally, I would use the manual shifting ability of the car to determine if the noise changes character with engine RPM at all. Everything "after" the transmission will change pitch/character with road speed (so being in 5th or 8th won't affect the noise). Everything "before" the transmission (including everything driven by the serpentine belt) will change pitch/character with engine speed (meaning that what gear you're in matters).

Some shops will also have a microphone set up where they can stick microphones all over the car near suspect components and then listen from a laptop in the car while its being driven. That could also confirm whether you're looking at alternator or not.

Work with passengers too to determine if the noise is from the front or rear etc...

Just my two cents - before spending a wad of money and possibly not fixing the problem. There was a guy in F10 forums earlier talking about a groaning or rumbling when the ED bar was lit. I believe it was his transfer case (completely unrelated to ED, but related to engine braking).

I was just thinking about this the other day...
BMW is really reaching with the “Regenerative Braking” designation...
What a crock. “Smart Charging” or something along those lines would be a more accurate descriptor.

[thakid22]

Originally Posted by cantstopthefeeling

Hi Thakid22,

Thanks for the quick reply. Any idea the rough cost on this? I was under the impression the alternator should charge at all times during driving rather than just when my foot is off the pedal and that light is illuminated. I'm not too familiar with the 535 set up though and could certainly be wrong. Also, I've noticed, I hear the sound a lot less when I go into Eco Pro mode.

I don’t know the price of an alternator replacement. It’s likely in the $1500 range, if done by BMW. An independent mechanic could probably do it for $600 to $900.

If you are handy, you can do it yourself at a substantial savings.

Still, we are just brainstorming/troubleshooting right now. It’s too early to run out and buy anything yet.

Are you sure the sound is coming from up front? Some sounds really travel around making it hard to pinpoint their location. The rear diff can whine. The transmission itself can produce a bit of whine too during acceleration or coasting.
I don’t have experience with X-drive, but I can imagine the transfer case could whine too.

Play around with the sound a bit more and see if you can duplicate it under other situations. Use manual mode to select 1st gear and coast down... do you still hear it? Turn the AC off. Still hear it?

All of that turbo plumbing under the hood can be a source of whistles and whines if there are leaks too.

The fact that you only hear it when the Efficient Dynamics display is lit seems ominous. The only sure change I can think of, that occurs with the light, is related to the alternators charging scheme.

Your dealer has a tool they can use to verify that it is indeed the alternator, before you spend time, effort, and money replacing it.

[HighlandPete]

Originally Posted by thakid22

I don’t know the price of an alternator replacement. It’s likely in the $1500 range, if done by BMW. An independent mechanic could probably do it for $600 to $900.

If you are handy, you can do it yourself at a substantial savings.

Still, we are just brainstorming/troubleshooting right now. It’s too early to run out and buy anything yet.

Are you sure the sound is coming from up front? Some sounds really travel around making it hard to pinpoint their location. The rear diff can whine. The transmission itself can produce a bit of whine too during acceleration or coasting.
I don’t have experience with X-drive, but I can imagine the transfer case could whine too.

Play around with the sound a bit more and see if you can duplicate it under other situations. Use manual mode to select 1st gear and coast down... do you still hear it? Turn the AC off. Still hear it?

All of that turbo plumbing under the hood can be a source of whistles and whines if there are leaks too.

The fact that you only hear it when the Efficient Dynamics display is lit seems ominous. The only sure change I can think of, that occurs with the light, is related to the alternators charging scheme.

Your dealer has a tool they can use to verify that it is indeed the alternator, before you spend time, effort, and money replacing it.

Good advice... must fault find first.

[cantstopthefeeling]

Originally Posted by HighlandPete

Can't hear anything on the video ???

Was there any change with increasing engine revs? (More load on the alternator).

The pitch coming from this video is very high from the intervals that I mentioned before, 8:15 to 8:33. Depending on your ears and your age, there is a chance you may not be able to hear this pitch as the upper limits of our hearing range can diminish with age. Also, if you have quality headphones, I'd recommend listening in those as your regular computer speakers may not be able to reproduce the high pitch(I suspect it's around 15kHz to 20kHz. I have asked 3 friends, 2 can hear it and one can't and they are all around their early 30's so please don't take offense as I'm not trying to call anyone old! In fact, I had one friend in middle school that couldn't hear the "dog whistle ring tone" all the kids would use on their phones so that they could hear the phone ring but the teachers couldn't as they were obviously older in age.

There is no change in pitch or intensity/volume at all. It's a very constant high pitch noise. Honestly, it sounds 100% unrelated to any type of mechanical sounds. For example, a "supercharger whine" sounds nothing like what i'm experiencing. It's not a "Buzzing" sound either, but rather a steady high pitch frequency that I suspect is near the upper limits of the human ear. I would relate it to a hearing test where they continuously play, with headphones, a high pitch frequency until you can no longer detect the sound. It makes 0 difference if i'm doing 5mph or 75mph. Again, it's only happening when that blue ED button is lit. I've confirmed the sound also happens every single time. In ECO pro mode, it happens a whole lot less and mostly only noticeable when going very slow approaching a stop sign with slight braking. It's when the ECO PRO mode goes to the far left indicating "charge" instead of "power." Engine RPM is irrelevant as even 1% throttle shuts off the sound (also the EfficentDynamics light shuts off with any type of throttle)

Passengers in the car can't seem to hear it. I will have a friend drive me in the car tomorrow and I will see if I can hear the sound when sitting in the backseat. It seems as if the sound is almost coming exactly from the instrument cluster. Is there anyway the display under the speedo and tach could be creating this sound when the alternator is pumping full voltage to the car?

[cantstopthefeeling]

Originally Posted by thakid22

I don’t know the price of an alternator replacement. It’s likely in the $1500 range, if done by BMW. An independent mechanic could probably do it for $600 to $900.

If you are handy, you can do it yourself at a substantial savings.

Still, we are just brainstorming/troubleshooting right now. It’s too early to run out and buy anything yet.

Are you sure the sound is coming from up front? Some sounds really travel around making it hard to pinpoint their location. The rear diff can whine. The transmission itself can produce a bit of whine too during acceleration or coasting.
I don’t have experience with X-drive, but I can imagine the transfer case could whine too.

Play around with the sound a bit more and see if you can duplicate it under other situations. Use manual mode to select 1st gear and coast down... do you still hear it? Turn the AC off. Still hear it?

All of that turbo plumbing under the hood can be a source of whistles and whines if there are leaks too.

The fact that you only hear it when the Efficient Dynamics display is lit seems ominous. The only sure change I can think of, that occurs with the light, is related to the alternators charging scheme.

Your dealer has a tool they can use to verify that it is indeed the alternator, before you spend time, effort, and money replacing it.

I'm hoping to provide a bit more insight with this post. I did a little more testing. When I'm in ECO PRO mode, I can only hear the noise when the battery is charging. (Please see attachment)

Also, I dimmed the cluster lights while listening to the noise and it made no difference so I'm starting to doubt the LED screen under the tach and speedometer is the problem. I'm going to try and drive another F10 535i xDrive and see if I can replicate what I'm hearing in another one. I'm almost hoping I can so that I can confirm my specific car doesn't have a problem, but I would be really surprised if BMW's engineering team would mass produce cars knowing the sound is present.

[HighlandPete]

Originally Posted by cantstopthefeeling

The pitch coming from this video is very high from the intervals that I mentioned before, 8:15 to 8:33. Depending on your ears and your age, there is a chance you may not be able to hear this pitch as the upper limits of our hearing range can diminish with age....

There is no change in pitch or intensity/volume at all. It's a very constant high pitch noise. Honestly, it sounds 100% unrelated to any type of mechanical sounds...

Passengers in the car can't seem to hear it. I will have a friend drive me in the car tomorrow and I will see if I can hear the sound when sitting in the backseat. It seems as if the sound is almost coming exactly from the instrument cluster. Is there anyway the display under the speedo and tach could be creating this sound when the alternator is pumping full voltage to the car?

Too old to hear it then... Does bring back memories of when I was a child and father had a friend who was a sound engineer. Remember when he showed my father how, as you get older, folks can't always hear higher frequencies. I could easily hear the high frequency sounds he dialled in, but the two adults couldn't.

What you are saying, it doesn't sound like a typical alternator fault, we'd all hear that no problems at all. While reading your post, I was starting to think maybe you have some unusual electrical interference type sound. Besides the thinking of something in the instrument panel, not a possibility it is coming through the speakers is there?

Wonder if it is generated when the alternator/charging system goes to the higher voltage (~14.8 volts) used in the overrun charging phase.

[Surly73]

One of the points I was trying to make earlier is that with the way ED works, if the battery is <80% SOC, nothing may in fact be changing when the blue bar lights so the correlation may be false.

I have a $2 direct-from-china digital lighter-socket voltmeter in the car so it's easy for me to throw that in and see what's going on. It's a great tool for everyone to have in the car to see if anything weird is going on. Anyways - a lot of people might be surprised that they're at 14.8VDC "regenerative braking" all the time.

If there's no change in system voltage because it's high-charging all the time, then it's time to chase something other than the alternator. If road speed has no bearing, that rules out a lot of stuff too, frankly. Maybe it's a fuel pump thing and when the engine fuel consumption goes to zero there's a noise? A lot of fuel pumps make some really high pitched noises.

[cantstopthefeeling]

Originally Posted by Surly73

One of the points I was trying to make earlier is that with the way ED works, if the battery is <80% SOC, nothing may in fact be changing when the blue bar lights so the correlation may be false.

I have a $2 direct-from-china digital lighter-socket voltmeter in the car so it's easy for me to throw that in and see what's going on. It's a great tool for everyone to have in the car to see if anything weird is going on. Anyways - a lot of people might be surprised that they're at 14.8VDC "regenerative braking" all the time.

If there's no change in system voltage because it's high-charging all the time, then it's time to chase something other than the alternator. If road speed has no bearing, that rules out a lot of stuff too, frankly. Maybe it's a fuel pump thing and when the engine fuel consumption goes to zero there's a noise? A lot of fuel pumps make some really high pitched noises.

Ok, so next I am going to get a lighter socket voltage reader. I will report back the voltage before hearing the sound, and will see exactly what the voltage is when I start to hear the sound. I suspect there might be a difference, but we will see soon! Thanks again everyone for chiming in. I really would love to get this resolved.

[HighlandPete]

Originally Posted by cantstopthefeeling

Ok, so next I am going to get a lighter socket voltage reader. I will report back the voltage before hearing the sound, and will see exactly what the voltage is when I start to hear the sound. I suspect there might be a difference, but we will see soon! Thanks again everyone for chiming in. I really would love to get this resolved.

I've also got a plug-in voltmeter which I use every few weeks as a check. My car typically settles to 14.3 - 14.4 volts after a few miles driving. When I lift off the gas it will change to 14.7 - 14.8 volts.

[GrabacrOne]

I have the same high pitch noise coming from my 2014 535i. It comes on when I lift off the gas and coast and the EfficientDynamics bar goes blue - like you described. When I apply the brakes and the ED bar goes to neutral, the sound goes away. It is exactly tied to status of ED given by the display in the instrument cluster. What actually changes in the drivetrain, I'm not sure. I can clearly hear but my SA cannot seem to pick it up. Even when the radio is on and the A/C is turned up, the frequency is so high I can hear it above everything else.

I have not tried to troubleshoot the issue much but I've had the sound since I've had the car - I just assumed it was a normal sound for all F10s. Please let me know if you trace the problem.

[Bklynjoker]

Are you hearing the AWD whining noise & confusing it for a problem? I came from a E70 X5 3.5i (same engine) and never heard AWD xDrive whining until I got in my F10.

[HighlandPete]

Originally Posted by Bklynjoker

Are you hearing the AWD whining noise & confusing it for a problem? I came from a E70 X5 3.5i (same engine) and never heard AWD xDrive whining until I got in my F10.

Don't think it will be a transmission whine, as the description doesn't fit.

Originally Posted by cantstopthefeeling

There is no change in pitch or intensity/volume at all. It's a very constant high pitch noise.....

.... It makes 0 difference if i'm doing 5mph or 75mph. Again, it's only happening when that blue ED button is lit.

...Engine RPM is irrelevant as even 1% throttle shuts off the sound (also the EfficentDynamics light shuts off with any type of throttle)

A transmission whine will change with speed and load. Whatever it is, it does appear related to how the energy management is working on the over-run, or throttle at zero position/input.

[Surly73]

Originally Posted by HighlandPete

I've also got a plug-in voltmeter which I use every few weeks as a check. My car typically settles to 14.3 - 14.4 volts after a few miles driving. When I lift off the gas it will change to 14.7 - 14.8 volts.

..which means that your battery state of charge is >80%

If it wasn't, you'd see 14.8VDC all the time, regardless of the "regenerative braking" marketing light.

[HighlandPete]

Originally Posted by Surly73

..which means that your battery state of charge is >80%

If it wasn't, you'd see 14.8VDC all the time, regardless of the "regenerative braking" marketing light.

Yes, that will be the case. I do use a CTEK charger several times in winter months, to keep the SOC in the 80% range. My normal summer use does keep the battery >80%.

[nedmon]

Another approach to chasing down a noise issue is to jack up the car and pop the hood and run the car up to "speed" so you can get closer to the source of the noise. Use a long tube to your ear as a listening aid.

You should take off the wheels so they are not hanging down and ah, stretching the suspension AND chock the wheels that are on the ground.